Assessing nitrogen supply potential and influence on growth of lettuce and 'Amaranthus' of different aged composts

Abstract

This study assessed the potential of different composts at different maturity stages to supply N and their effect on the vegetative growth of lettuce and 'Amaranthus'. Five composts aged 1, 3, 6, 9, and 12 months, were mixed with soil @ 5%, 10% and 15% then seeded with lettuce and 'Amaranthus'. Results showed that 1, 3 and 6 month aged composts had a negative effect on plant height of lettuce and 'Amaranthus' as 1–15.78% and 4.78 to 29.45% decrease in plant height over control was recorded respectively. On the other hand 9 and 12 month aged composts had a significant positive effect on plant height of lettuce and 'Amaranthus' where 43.48% and 34.8% increase over control was recorded with the application of 15% of 12 month aged compost respectively. A similar effect was observed on fresh biomass of both lettuce and 'Amaranthus' where a 386% and 59.43% increase over control was recorded with the application of 15% of 12 month aged compost respectively. One and three month aged composts revealed a negative effect on N absorption by lettuce whereas 1, 3, 6 and 9 month aged composts had a negative effect on N absorption by 'Amaranthus'. 30.39% and 21.48% increases over control in N absorption by lettuce and 'Amaranthus' respectively were recorded with the application of 15% of 12 month aged compost.